This discussion reviews the current status of behavioral intervention with adult and pediatric cancer patients. It begins by describing the recent entry of behavioral research and practice into comprehensive cancer treatment. The discussion then examines the use of behavioral procedures to control aversive side effects of treatment. Although the control of chemotherapy side effects is the primary focus (most of the behavioral research on symptom control has dealt with reduction of nausea and vomiting with chemotherapy), the application of behavioral principles to other side effects (i.e., anxiety and pain) associated with the aggressive treatment of cancer is assessed. The third topic is behavioral intervention to control child distress during invasive procedures. The discussion ends with a consideration of new directions of research and practice.